Karst Geology Research Articles

Environmental and engineering problems of karst Geology in China

Karst terrane is generally regarded as a fragile and vulnerable environment. Its underground drainage system can aggrevate both drought and flood problems; the lack of filtration in an underground conduit makes waste disposal more difficult; and the lack of soil cover in bare karstland can enhance deforestation. Moreover, karst terranes are quite often haunted by a series of engineering problems, such as water gushing into mines or transportation tunnels; leakage from reservoirs; and failure of building foundations. In China, there are more than 200 cases of karst collapse, which include many thousands of individual collapse points. Some of these are paleo and natural collapses, but most of them are modern collapses induced by human activities and they have caused serious damage. Many factors such as geologic structure, overburden thickness and character, lithologic features of karstified rock, and intensity of karstification are related to development and distribution of modern collapses. However, China's karst is mainly developed in pre-Triassic, old phase, hard, compact, carbonate rock. Consequently most modern collapses have occurred only in the overlying soil. So it is understandable that the fluctuation of the water table in the underlying karstified strata plays an important role in the process of collapse. Nevertheless, there are different explanations as to how the groundwater activities can induce collapse.

THERMAL INFRA‐RED TECHNIQUE APPLIED TO MODERN INVESTIGATION*

AbstractDuring the last few years a substantial improvement has been made in the development of the thermal infra‐red scanner so that 1.5 milli‐radian resolution is now commonly obtained. Direct transfer of information on 70 mm film through fiber glass transcoder allows immediate and refined interpretation.Although the collected data represent the image of thermal anomalies within a pellicular section of the earth's crust, it is proved that because of “per ascensum” phenomena, deep buried sources induce surface thermal changes. The difficulty lies in showing an absolute relationship between these deep phenomena and thermal surface occurrences.A careful examination of several cases related to hydrology, karstic geology, civil engineering, pollution, hot springs should help the geophysicist by providing him a new tool for shallow investigations. Thermographics with interpretation are shown to support this statement.

Megalithic Quarrying Techniques and Limestone Technology in Eastern Spain

Evidence in Eastern Spain and in the Balearic Islands indicates that during the building period of the megaliths and thereafter the inhabitants of this region developed a considerable limestone technology. This technology embraced an empirical knowledge of carbonate chemistry and karst geology which enabled them to quarry large limestone blocks to gain a maximum of usable material with a minimum of effort. It appears that one of the quarrying methods used was based on the chemical dissociation by fire of standing stone blocks at their attachment points, a technique hitherto unknown or unreported in the literature. Throughout the interval of megalith occupation there is evidence of the exploitation of limestone for a wide variety of purposes, including the making of objects such as containers, querns, and funereal vessels. Ultimately, their experiments led to a unique burial practice in which the dead were cremated by means of quicklime.The quarrying methods used by the Iberian megalith builders are described below. Most of the specifics of their methods will be drawn from one well studied site, Son Carla on the island of Menorca, but similar quarries have been identified at numerous sites in the Balearic Islands and at Sisante in La Mancha on the mainland.

A Possible Contaminant Contribution To TheYucatan Karstic Aquifer

The rapid growth and diversification of assembly plants in Yucatan, Mexico, has resulted in the predomination of industries that use significant quantities of hazardous substances. Untreated chemicals and toxic wastes have been injected directly to the karstic aquifer system using deep boreholes, caves and cenotes or artificial lagoons, but the disposition of the majority of generated waste from these industries is unknown. National legislation and regulations exist in Mexico that address waste generation and disposition but, even if industries comply with them, adequate facilities do not exist to properly treat, recycle, or dispose of the waste they generate. In Yucatan, although the entire population depends on groundwater, the aquifer system is viewed as one where contaminants are easily transported underground and through groundwater flow because of its karstic geology and low attenuation capabilities. Contaminant migration has been analyzed using a solute, continuously injected in the area of Merida, 36 km from the coast, which is known to be mobile in groundwater systems. Results show that the potential is high for delivery of chemicals along the shoreline via groundwater; therefore, contamination becomes a problem of concern because, through mismanagement, waste can seep into groundwater with serious environmental and public health ramifications. Transactions on the Built Environment vol 9, © 1995 WIT Press, www.witpress.com, ISSN 1743-3509